Coking of hydrocarbon oils



Oct. 27, 1959 J. T. CABBAGE 2,910,425

COKING 0F HYDROCARBON OILS Filed Dec. 31, 1954 2 Sheets-Sheet 2 FIG. 4. 0

[I m m m INVENTOR m .J.T. CABBAGE P #5 "I BY 2 llw W 5 3 7 5 LL HT: ATTORNEYS Patented Oct. 27, 1959- 2,910,425 COKING F HYDROCARBON OILS John T. Cabbage, Bartlesville, 0kla., assignor to Phillips Petroleum Company, a corporation of Delaware Application December 31, 1954, Serial No. 479,073 19 Claims. (Cl. 208--53) This invention relates to the conversion of hydrocarbon oils. In one of its aspects this invention relates to a method for coking hydrocarbon oils employing a fluidized bed of finely divided solids. In another of its aspects this invention relates to apparatus for the coking of hydrocarbon oils.

In recent years various processes have been developed for coking residual oils and other types of heavy hydrocarbon oils. These processes have included both moving bed processes and fluidized bed processes wherein coke formation is caused to occur on the particles of contact material in the bed. However, one serious difiiculty which has beset practically all of the prior art processes is agglomeration of the particles carrying the partially coked oil, i.e., the particles are no longer free-flowing but are agglomerated into clumps. Such agglomeration not only causes operating ditficulties but also prevents production of a uniform quality product where the coke is recovered as a product of the process.

I have found that agglomeration can be prevented by diluting the contact bed with additional clean hot contact material before the coking has proceeded to the point where agglomeration sets in.

It is an object of this invention to provide a method for the coking of hydrocarbon oils.

It is another object of this invention to prevent agglomeration of the particles of a contact bed in a coking process employing a bed of contact material for coking a hydrocarbon oil.

Another object of this invention is to provide a hard, dense, dry petroleum coke which finds a ready use in industry.

Another object of this invention is to provide apparatus for carrying out the above objects.

Still other aspects, objects and advantages will be apparent to those skilled in the art upon reading this disclosure.

According to the invention there is provided a method for coking an oil which comprises: maintaining a dense fluidized bed of contact solids in a coking zone under coking conditions; introducing an oil to be coked into said coking zone in a manner and amount so as to form a coat of oil on said contact solids; at least partially coking said coat of oil; overflowing coated contact solids from said coking zone into a calcining and stripping zone; introducing a stream of clean hot contact solids into the upper portion of said calcining and stripping zone; completing the coking of any remaining uncoked oil on said solids; calcining and stripping said coke covered solids; withdrawing vapors from an upper portion of said zones; and withdrawing free-flowing contact solids covered with a layer of coke from said calcining and stripping zone.

It is to be noted that the stream of clean hot contact solids is introduced into the upper portion of the calcining and stripping zone. Preferably said stream of clean hot contact solids is introduced at a point or points adjacent the point or points of overflow of the coated solids from the coking zone, sons to immediately contact, and mix with, said overflowing solids. When said clean contact solids mix with said overflowing coated solids two important steps in the process are accomplished (1) the clean contact solids dilute the coated contact solids, i.e., the clean contact solids go between or spread apart the coated contact solids which are coated with. a layer of at least partially coked reduced oil, and (2) additional heat is supplied to said overflowing coated solids. Thus by diluting, and supplying additional heat immediately to said overflowing stream of coated contact solids, agglomeration is prevented.

It is presently preferred that the additional heat supplied by the stream of hot clean contact solids be sufficient to substantially increase the temperature of the overflowing stream of coated contact solids in order to aid in completing the coking/ or calcine said coke. How ever, the invention is not so limited. Thus, the clean contact solids can be introduced at a temperature just sufiicient to compensate for heat absorption due to endothermicity of the reaction without necessarily increasing the temperature. In such instances it will. generally be desirable to increase the residence time in the calcining and stripping zone. In one embodiment of the invention, discussed further hereinafter, provision is made for increasing the residence time of the coated contact solids in the calcining and stripping zone.

The term reduced oil as used herein and in the claims refers to an oil which has been reduced in volume, i.e., it is a residue which remains after a oil is removed, as by vaporization.

Further, according to the invention there is provided an apparatus for coking an oil which comprises: a coking vessel adapted to contain a fluidized bed of contact solids J and means for maintaining said fluidized bed, said vessel having a central section and an annular section surrounding said central section; means for forming a layer or coat of oil to be coked on said contact solids in said bed; means for supplying additional heat and contact solids to said fluidized bed as it flows from one of said sections to theother of said sections; andmeans for withdrawing Figure 2.

Figure 2 is a diagrammatic illustration of a presently preferred type of coking vessel.

Figures 3 and 4 are diagrammatic illustrations of other coking vessels of the invention.

Referring now to the drawings the invention will be more fully explained. Corresponding reference numerals are employed to denote correspond-ing elements where possible.

Referring to Figure 2, coker vessel 10 is a vertical substantially cylindrical vessel having a top outlet 11 for gaseous fluids and a bottom 12 in the shape of an inverted cone, terminating in a first conduit inlet 13 at its lower end. Arranged coaxially Within said vessel 10, and in the lower portion thereof, is an inverted conical out let member 14. Said conical outlet member 14 is spaced apart from the inner wall of vessel 10. A vertically arranged elongated annular sleeve member 15, in sealed contact with the upwardly directed base of said conical outlet member 14, extends a distance above said base so as to provide an annular space or section 16 between said portion of the original inlet 1 and thus' maintain a dense fluidized bed of said solids. in. annular space 16. A second conduit inlet 19 By; thusidistributing: said second incoming stream of finely.

divided.solidsit immediately contacts and mixeswith the stream-of coated solids-overflowing the top-of annular. sleeve 15 from annular space 16'.

.Oil: inlet conduit 21- extends into vessel lliiand is in communicationwith spray ring-22 mounted by means'of supports124 on the outer wall of'sleeve member lS, in annular space 16; below the top of; andwithin the fluidized bed of finely; divided solids maintained in said' annular space-.16. Oil spray ring 22' isthus arranged'and adapted to-spray the incomingfeed'oil into said bed fromia locus of points within said bed. If desired oil'spray ring 22 canrbe arrangedand adapted to spray said oilfeed from a point above and downwardly onto" the top of said bed similarlycas shown and described inconnection with Figure:.3. While the means of introducing the oil feedis shown as a spray-ring it is to be understood that other means of introducing theoilfeedcan beemployed. The only requirement being that the-oil is introduced'in a manner'and amount-so as'to'form-auniform layer or coat of said oil on said solids.-

Positionedin the lower-portion of-central space 17 are a plurality of: inlets 23 for introduction of a suitable stripping. fluid, preferably steam. While not shown in Figure. 2; it is tobe understood that, if desired; ahorizontally. extending perforated plate can be provided. across the upper end of conical outlet member'1'4" similarly as in; Eiguresafl. and 4, and a-fluidized-bed maintained in central space 17. In such instances suitable downcomer space isaprovided 'around the' periphery of said-perforated plate, within said annular-sleeve member 15, in order to permit thecoke covered solids to be withdrawn through conical outlet member 14 In operation, cokervessel 10 f Figure 2is employed as a part of a system as schematically shown in Figure 1. Hot finely divided solids. fluidized and'carried in a st eam of steam are introduced into coker vessel through inlet conduit 13 andperforated plate 18 to' establish a dense fluidized bed of said solids in annular space 16. Hydrocarbon oil to be coked is introduced via conduit 21 into spray ring 22 and is sprayed. into saidbed'in-the form of finely divided droplets .so asto form a' layer or coat of oil on the finely divided solids of said bed. The fine y divided solids carrying said coat ofo'il are maintained in annular space or section 16 sufficientlylong to at least partially coke the oil on the surface thereof. The level of the dense phase fluidized bed is-maintained at or slightly above the top of annular sleeve '-and due to the turbulent nature of a'fluidized bed a portion of the coated solids overflow into central space or section-17; The height of the fluidized bed in annular space 16 is a function of the type of solids being fluidized, the velocity of the fluidizing medium, and other factors well known to those skilled'in the. art. As. the overflowing coated solids enter central section 17, or immediately thereafter; they are contacted with astream of clean hot finely divided solids introduced through conduit inlet 19, and evenly distributed around theinner top portion of annular sleeve 15by means of .cone shaped defiectorZt). The stream of clean solids thus. immediately contacts and .mixes with the overflowing. stream. to supply additional heat to and dilute the coated solids, thereby preventing'agglomeration of the coated'solids. The 'additional heat"supplied by the introducedrstream of clean -solids'serves'to complete the coking of any remaining uncoked oil on said coated particles and also to calcine said coke. In central section 17 the combined stream of solids is stripped by means of strlpping fluid introduced through inlets 23. superheated steam is a presently preferred stripping fluid although other inert gases can be used.

Coke covered finely divided solids are withdrawn reheater 27 through-standpipe 29 and introduced into" conduit 39 wherein they are fluidized by means'of' steam from line 31, to form the stream of flnelydividedsolids introduced into coker 10 through inlet conduit 13 as de' scribed above. solids withdrawn from reheater 27 can be controlled by meansof cooler 32 which can also be a steam generator, said'steam beinga product of the process;

and line 33.

Vapors. from coker vessel 10 are withdrawn through" separation means 34 andpassed through line 11 into fractionation zone 35 from which product streams' comprising'a stream of high BTU gas, a stream'of naphtha;

a stream of gas oil and a stream of heavy gas oil or'fuel oil are recovered asshown. If desired, said heavy gas oil or fuel oil can be recycled by means of line 36'into line2'1' and thereby returned to coker 10 for coking. This recycle of the heavygas oil or fuel oil fraction provides a means of converting the originalhydrocarbon oil feed intocoke and distillate products only, i.e., the fuel is recycled to extinction.

When finely divided coke-is employed as the finely divided heat carrying solid of the process, a stream of said finely divided cokecan be withdrawn front coker 10 through conduit 37 as a coke product of the process. Said coke product is a hard, dense, petroleum coke whichfinds a ready market such as for the manufacture-of electrodes for the aluminum industry. When finely divided coke is employed in the system, the burning in reheater'27'is'controlled so as to not completely burn the coke particles but'only to burn the excess coke; i.e., the coke layed down on the particles in coker 10. The nucleus or.

original coke particles are then recycled in the system as" described.

Figure 3' illustrates a modification of the coker vessel 10'.

of Figure 2. In this modification inverted conical member 14 is provided at its upper end with a' horizontally extending perforated distributor plate: 38. Said plate serves to distribute the fluidized stream of finely divided" solids introduced through inlet member 14 and thus mail'itain a dense fluidized bed within annular sleeve 15, which. is in sealed contact with the peripheryof said distributor.

plate 38. The upper end. of annular sleeve 15' is provided witha plurality of vertically extending recesses'39 having horizontally extending weir bottoms. for. directing.

overflow of solid. particles from central space; 17- into annular space 16. A plurality ofinletconduits 40, 41, 42, and 43 are providedandarranged to. discharge additional streams of hot fluidized. finely divided. solids into said annular space. immediately adjacent one-of said plu: rality of recesses so as to mixwith: the overflowing stream ofsolids as previously described; Oil feedring- 22 is arranged within annular sleeve 15 above the bottom of recesses.39- andv above the top of the fluidized bed so as to. spray oil downwardly onto the top of the fluidized.

contact bed.

In ,the :operationof the system. shown in Figure *1, em-v pl ying .the modification. of coker vessel. 10-. shown in: Fige:

ure 3, the, junctions of inverted conical member 14 and The temperature of the finely divided.

Combustion. gasesare withdrawnifrom reheater 27 throughinternally' arranged separation means, such as cyclones (not shown) conduit 13 are reversed. In the coker of Figure 3 the fluidized bed is maintained within central space 17 insteadof in annularspace 16 as in Figure 2. Therefore, the streamof finely divided solids from reheater 27, used to maintain said bed, is introduced through inverted conical inlet member 14 and line 31 is connected to said member 14 as shown inFigure 3; and line 25 is connected to outlet 13in order to convey coke covered solids to reheater 27. Thus in operation of the coker vessel of Figure 3 regenerated contact solids from reheater 27 are introduced through inlet member 14, the fluidized bed is maintained within central space 17, said bed overflows into annular space 16 and is withdrawn through outlet13. As they coatedsolids' overflow into annular space 16 they are immediately contacted with hot clean finely divided solids introduced from reheater 27 through conduits 40, 41, 42 and 43. Ifdesired the temperature of said solids in said conduits can be controlled by means of heater 50, 51, 52 and 53 respectively (see Figure 1). If desired a portion of the coke covered solids can be Withdrawn through outlets 37 and 37'.

I Figure 4 illustrates a further modification of the'coker vessel'lo of Figure 2. This modification is similar to, but different from that shown in Figure 3 in two re- Spects. (1) In this modification oil feed ring 22 is arranged and adapted to spray the oil feed into the fluidized bed maintained within annular sleeve 15. (2) There is provided an annular perforated distributor plate 44 which extends horizontally from the inner wall of vessel 10 acrossannular space 16 in the same plane as the lower end of! annular sleeve member 15. The extended end of said plate 44 is spaced apart from said sleeve member so as to provide a downcomer space 45. Stripping fluid is introduced into annular space 16 through inlets 23 from below said plate 44. Thus a fluidized bed can be maintained in the calcining and stripping zone (annular space 16) in those instances where a longer residence time is desirable in said zone as previously discussed. The remainder of the construction and operation of the coker vessel is the same as that described for the coker vessel of Figure 3.

While the top of annular sleeve member 15 has been shown as provided with a plurality of recesses in Figures 3 and. 4, said recesses can be omitted, as in Figure 2, if desired. However, the recessed construction is presently preferred because it provides better contact and mixing of the overflowing solids with the additionally introduced solids.

The coker vessel 10 of Figure 2 is presently preferred because (1) the calcining and stripping zone is positioned in the center of the vessel and is insulated against heat loss by the surrounding annular coking zone, (2) with the oil feed ring positioned within the fluidized bed of the, coking zone there is better distribution of the oil on the, contact solids and less wet" coke in the overflowing stream, and (3) deflector cone provides better immediate contacting and mixing of the overflowing cokecovered solids, and the additionally introduced clean solidsr A wide variety of oils canbe processed according to the invention. Such oils include reduced crudes obtained from crude oil distillation, cracking still tars or residues, vacuum still tars or residues, etc. Such heavy oils are usually preheated prior to their introduction into the coking vessel.'- The temperature to which they are preheated depends upon the nature of the oil but will gen erally range from 300 to 1000 F., and preferably from 650 to 850 F. When an extremely heavy oil, tar or pitch is being coked, its viscosity can be still further reduced by dilution with a lighter hydrocarbon such as a gas oil or kerosene.

The particulate material or finely divided solids employed can be any heat resistant material. It is preferably an inert material. Finely divided coke is a presently preferred material. Other particulate materials which can be employed are crushed fire brick, spent catalysts, clay, etc. The particulate material can be porous or non-porous. The particle size can be in the range of 10 to 500 microns, preferably 10 to 200 microns and still more preferably 50 to 70 microns. Operating conditions will vary according to the oil being coked. The temperature of the fluidized bed into which the oil feed is introduced is usually maintained within the range of 650 to 950 F., preferably 750to850" F. The temperature of the calcining and stripping zone is usually maintained within the range of 850 to 1600 F., preferably 950 to 1300 F. These temperatures, while dependent to some extent on the temperature of the oil feed, are largely controlled by the incoming streams of fluidized solids. The temperature of the incoming fluidized solids which maintain the fluidized bed in the coking zone will usually range from 650 to 950 F., preferably 750 to 850 F. The temperature of the additional finely divided solids added to and mixed with the overflowing solids will generally be substantially higher, within the range from 850 to 1600 F., preferably 950 to 1300 F. The temperature in reheater 27 is usually maintained within the range 1000 to 1700 F.

The apparent density of the fluidized beds'will range from. 10 to 50, preferably 20 to 50 pounds per cubic foot, and the velocity of the fiuidizing medium flowing upwardly through the bed will have a superficial linear velocity between about 1 to 5, preferably 1 to 2 feet 'per second. The weight ratio of oil feed charged, to solids charged to the coking'zone will range from 1:5 to 1:10, preferably from 1:7. The weight ratio of clean solids added to overflowing solids will range from 0.5:1 -to" The following example further illustrates: the invention.

Example A 10 A.P.I. gravity vacuum reduced topped crude from Western Kansas crude oil, at a temperature .of approximately 725 F. is sprayed into a dense fluidized bed of finely divided coke (from a locus of points within the bed) maintained at a temperature of approximately 825 F., and having a particle size within the range of 10 to 200 microns, to form a thin coat of oil on said coke particles. The oil coated particles are maintained in said fluidized bed long enough to at least partially coke said oil and are then withdrawn from the coking zone by overflowing into an annular calcining and stripping zone. As the coated particles overflow into said calcining and stripping zone they are immediately contacted by, and mixed with, a stream of clean hot finely divided coke introduced at a temperature of approximately 1300 F. Coking of any remaining uncoked oil is completed and the coke covered particles are calcined and stripped in said calcining and stripping zone in the presence of superheated steam introduced at a temperature of about 1150 F. The temperature of the calcin-' ing and stripping zone is maintained at about 1100 F. The average apparent density of the fluidized bed in the coking zone is approximately 30 pounds per cubic foot. Steam is used as the fluidizing medium. A free-flowing stream of finely divided coke, covered with a layer of dry calcined coke, is withdrawn from the bottom of said calcining and stripping zone. Yields from this operation based on the oil charge are:

Gas wt. percent 8.3 Naphtha vol. percent 15.9 Gas oil vol. percent 24.2 Heavy gas oil vol. percent 32.7 Net coke wt. percent 27.5

As will be evident to those skilled in the art, various modifications of this invention can be made, or followed, in the light of the foregoing disclosure and discussion, without departing from the spirit or scope of the disclosure or from the scope of the claims.

:Iclaim:

1. A method of coking an oil which comprises: in-

troducing a first stream of hotfluidized finely divided contact solids ;.into a coking zone maintained under coking conditions to establish :a dense fluidized bed of said solids; introducing said oil into said bed .as a liquid, a 'portion of said oil being vaporized upon contacting said solids and causing an unvaporized'portion tocoat and adhere to said solids as a layer of oil which has been reducedin volume; at least partially coking said coat of oil; overflowing coated finely divided solids from said coking zone into a calcining and strippingzone; immediately contacting and mixing said overflowing solids, as they are overflowing, with a second :stream of hot finely divided contact solids introduced intoithe upper portion ofsaid calcining and stripping :zone at a temperature and in anamount sufiicient to prevent agglomerationof said coated solids; completing the coking of any remaining uncoked oil on said solids; calcining and stripping said-coke-covered solids in said calcining and stripping, zone; withdrawing vapors from an upper portion of said zones; and withdrawing free flowing contact solids covered with a layer of coke from said calcining and stripping zone.

L2. A-method according to claim 1 wherein said finely divided solids are finely divided coke.

.13. A method'according to claim 1 wherein said oil is sprayed from "a point above and downwardly onto the top ,of said dense fluidized bed,.and said second stream ofrhot finely divided solidsis introduced at a temperature substantially higher than said first stream of finely divided solids.

4. A method according to claim 1 wherein said oil is sprayed into said bed in a direction countercurrent to the general up-flow of said bed from a locus of points with in the upper portion of said bed, and said second stream of hot finelydivided solids is introduced .at a temperature substantially higher than said first stream of finely divided solids.

"5. .A method of coking an oilwhich comprises: introducinga firststream of hot fluidizeclfinely divided contact solids into a central coking zone maintained under coking conditions to establish a dense fluidized bed of said solids; introducing said oil into said bed as a liquid, a portion of said oil being vaporized upon contacting said solids and causing an unvaporized portion to coat and adhere to said solids as a layer of oil which has been reduced in volume; at least partially coking said coat of oil; overflowing coated finely divided solids from said central cokingzone ,into an annular calcining and stripping zone surrounding said central coking zone; immediately contacting and mixing said overflowing solids, as they are overflowing, with a second stream 'of hot finely'divided contact solids introduced into the upper portion of said calcining and stripping zone at a tern perature and in an amount sufl'icient to prevent agglomeration of said coated solids; completing the coking of any remaining uncoked oil on said solids in said calcining and stripping zone; calcining said coke on said solids; introducinga hot stripping medium into the lower portion of said calcining and stripping zone; stripping said coke covered solids; withdrawing vapors from said zones; and withdrawing free-flowing finely divided solids covered with a layer of coke from said calcining and stripping zone.

--6. A method 'accordingtoclaim 5 wherein said second stream of finely divided solids is introduced into the upper portion of said calcining and stripping zone at a plurality of points, each of which points is adjacent a point of overflow of said coated solids so as to immediately contact, admix with, and dilute said overflowing coated solids and thereby prevent agglomeration of said coated solids and said oil is sprayed from a point above and downwardly onto the top of said fluidized "bed in said central coking zone.

7..A'method of coking an oil whichrcomprises: intro tact solids into anannular coking zone maintained under coking conditions to establish a dense fluidized bed oftsaid solids; introducing said oil into said bed as a-liquid, a portion of said oil being vaporized upon contacting'said solidsand causing an unvaporized portion to coat and adhere to said solids as a vlayer of oil which has been reduced in volume; at leastpartially coking said coat-of oil; overflowing coated finely divided solids from said annular coking zone into a central calcining and stripping zone surrounded by said annular coking zone; immediately contacting and mixing said overflowing solids, as they are overflowing, with a second stream of hot finely divided contact solids introduced into the upper portion of said calcining and stripping zone at a temperature and in an amount sufiicient to prevent agglomeration of said coated solids; completing the coking of any remaining uncoked oil on said solids in-said calcining and stripping zoneg-calcining said coke on said solids; introducing a hot stripping mediuminto the'lower portion of said calcining and stripping zone; stripping said coke covered solids; withdrawing .vapors from said zones; and withdrawing freerflowing finely divided-solids covered with a layer of coke from sai'dcalcining and stripping zone.

8. A method according to claim 7 wherein. said second stream of finely divided solids is, introduced into theupper portion of said calcining and stripping zoneafrom a locus adjacent the locus of overflow of said=coated vsolids, and said oil is sprayed into'said bed in said coking zone from a locus of points within said bed.

9. A method according to clairnS whereina fluidized bed is maintained in'said calcining andwstriping zone.

l0.rA method according to claim 7 wherein a fluidized bed is maintained in said calcining and stripping'zone.

1.1. A method of coking an oil which.comprises;.introducing a first stream of hot fluidized finely divided coke having a particle size within the. range of .10 to 200 microns into an annular coking zone at 'a temperature within the range of 750 to 850 F. to establish a dense fluidized bed of said finely divided coke; introducing said oil at a temperature withinthe range of 650 to850 F. into said bed from a locus of points withinsaidvbed, the weight ratio of said oil to said finely divided cokebeing within the range of 1:5 to 1:10; a portion ofsaid oil being vaporized before substantial cracking occurs, cans ing an unvaporized portion of the oil to coat'and adhere to said coke as a layer of oil which has been reduced in volume; at least partially coking said coat of oil; overflowing coated finely divided cokefromsaid annular coking zone into a central calcining and stripping zone surrounded by said annular coking zone; introducing a second stream of hot finely divided coke at a temperature within the range of 950 to 1300 F. into the upper portion of said calcining and strippingzzoneso as to immediately contact, mix with and dilute said 'overflowing coated finely divided coke, the weight ratioof said second stream of hot finely divided coke to said overflowing stream of coated overflowing coke being within the range of 0.5:1 to 1.5: l; completing the coking 'of'any remaining uncoked reduced oil on said coke in said calcining and stripping zone; calcining said coke; introducing a hot stripping fluid into the lower portion of said calcining and stripping zone; stripping entrained volatile matter from said coke coveredfinely divided coke particles; withdrawing vapors from the upper portion of said zone and passing said vapors to a fractionation zone; and withdrawing a stream offree-flowing calcined coke particles from the bottom of said calciningand stripping zone as a product of the process.

12. An apparatus for the coking of a hydrocarbon oil which comprises, in combination: a vertical substantially cylindrical vessel adapted to contain a bed of fluidized solid particles,said vessel having a top outlet for gaseous fiuids and a bottom in the shape of an inverted cone terminating at its lower end in a first conduit; an inverted conical member arranged coaxially with and in the lower part of said vessel and spaced apart throughout its length from the inner wall and bottom of said vessel, said inverted, conical member terminating in a second conduit which extends through said bottom of said vessel above said first conduit; a vertically arranged elongated annular sleeve member in sealed contact with the upwardly directed base of said conical member and extend ing a distance above said base so as to provide a central space Within said sleeve member and an annular space between said inner wall of said vessel and said sleeve member, said annular space being in communication with said first conduit; at least one inletconduit in an upper part of said vessel arranged to discharge fluidized solid particles adjacent the top of said annular sleeve member; means for introducing said oil into the upper portion of one of said central space and said annular space; and a plurality of inlets for introducing stripping fluid into a lower portion of said vessel.

13. An apparatus for the coking of a hydrocarbon oil which comprises, in combination: a vertical substantially cylindrical vessel adapted to contain a fluidized bed of solid particles, said vessel having a top outlet for gaseous fluids and a bottom in the shape of an inverted cone and terminating in a conduit outlet for solid particles; an inverted conical inlet member arranged coaxially with and in the lower part of said vessel and provided at its upper end with a horizontally extending perforated distributor plate for distributing a first stream of fluidized solid particles introduced into said vessel, said conical member and perforated plate being arranged centrally of said vessel and spaced apart from the inner wall of said vessel; a vertically arranged elongated annular sleeve member in sealed contact with the periphery of said perforated plate and extending a distance above said perforated plate so as to provide an annular space between said inner wall of said vessel and said sleeve member; a plurality of fluidized solid inlet conduits extending into said vessel and arranged to discharge additional streams of fluidized solid particles into said annular space adjacent the top of said annular sleeve member; an oil inlet member arranged and adapted to spray said oil onto the top of a fluidized bed of solid particles maintained within said annular sleeve member above said perforated plate; and a plurality of inlets for introducing stripping fluid into the lower portion of said annular space.

14. The combination of claim 13 comprising, in addition: an annular perforated plate extending horizontaliy from the inner wall of said vessel across said annular space in the same plane as the lower of said annular sleeve member, the extended end of said annular perforated plate being spaced apart from said sleeve member.

15. The combination of claim 13 wherein the upper end of said annular sleeve member is provided with a plurality of vertically extending recesses having horizontally extending weir bottoms for directing overflow of said fluidized bed of solid particles from within said annular sleeve member into said annular space, and each one of said plurality of fluidized solid inlet conduits is positioned so as to discharge a stream of fluidized solid particles into said annular space immediately adjacent one of said plurality of recesses.

16. An apparatus for the coking of a hydrocarbon oil which comprises, in combination: a vertical substantially cylindrical vessel adapted to contain a fluidized bed of solid particles, said vessel having a top outlet for gaseous fluids and a bottom in the shape of an inverted cone terminating in a first conduit inlet for a first stream of fluidized solid particles; an inverted conical outlet member for solid particles in central, spaced apart arrangement with the inner wall of and said bottom of said vessel, said inverted conical member terminating in a second conduit which extends through said bottom of said vessel above said first conduit; a vertically arranged elongated annular sleeve member in sealed contact with the upwardly directed base of said conical member and extending a distance above said base so as to provide an annular space between said inner wall of said vessel and said sleeve member, and a central space within said sleeve; an annular perforated distributor plate, extending horizontally from the lower end of said sleeve member across said annular space to the inner wall of said vessel, through which said first stream of fluidized solid particles is introduced into said annular space; a second conduit inlet extending into and terminating in a downwardly directed L positioned at the center of said vessel; a cone shaped deflector member, of smaller diameter than said annular sleeve, arranged within said annular sleeve below said L, the base of said deflector member being below but in close proximity to the top of said sleeve member so as to distribute a second stream of fluidized solid particles, introduced through said L, adjacent the inner top portion of said annular sleeve; an oil inlet member arranged and adapted to introduce said oil into the upper portion of a bed of fluidized solid particles maintained within said annular space above said perforated plate; and a plurality of inlets for introducing stripping fluid into the lower portion of said central space.

17. The combination of claim 16 wherein said oil inlet member is within said annular space and adapted to spray said oil into said fluidized bed of solid particles maintained within said annular space in a downward direction countercurrent to the general outflow of said bed.

18. The combination of claim 13 wherein said oil inlet member is positioned within said annular sleeve and adapted to spray said oil into said fluidized bed of solid particles maintained Within said annular sleeve.

19. In a hydrocarbon conversion zone maintained under coking conditions and wherein there is a central section surrounded by an annular section, the method of coking an oil which comprises: introducing a first stream of hot fluidized finely divided contact solids into one of said central and said annular sections to establish a dense fluidized bed of said solids; spraying said oil into said bed from a locus of points within said bed, a portion of said oil being vaporized upon contacting said solids and causing an unvaporized portion to coat and adhere to said solids as a layer of oil which has been reduced in volume; at least partially coking said coat of oil; overflowing coated finely divided solids from said section containing said fluidized bed into the other of said central and said annular sections, said other section being a calcining and stripping section; immediately contacting and mixing said over-flowing solids, as they are overflowing, with a second stream of hot finely divided contact solids introduced into the upper portion of said calcining and stripping section at a temperature and in an amount sufficient to prevent agglomeration of said coated solids; completing the coking of remaining uncoked oil on said solids in said calcining and stripping section; calcining said coke on said solids; introducing a hot stripping medium into the lower portion of said calcining and stripping section; stripping said coke covered solids; withdrawing vapors from said sections; and withdrawing free-flowing finely divided solids covered with a layer of coke from said calcining and stripping section.

References Cited in the file of this patent UNITED STATES PATENTS 2,457,232 Hengstebeck Dec. 28, 1948 2,550,922 Gullette May 1, 1951 2,687,992 Leffer Aug. 31, 1954 2,689,787 Ogorzaly Sept. 21, 1954 2,690,990 Adams Oct. 5, 1954 2,709,675 Phinney May 31, 1955 2,862,871 Smith Dec. 3, 1958 

1. A METHOD OF COKING AN LIL WHICH COMPRISES: INTRODUCING A FIRST STREAM OF HOT FLUIDIZED FINELY DIVIDED CONTACT SOLIDS INTO A COKING ZONE MAINTAINED UNDER COKING CONDITIONS TO ESTABLISH A DENSE FLUIDIZED BED OF SAID SOLIDS; INTRODUCING SAID OIL INTO SAID BED AS A LIQUID, A PORTION OF SAID OIL BEING VAPORIZED UPON CONTACTING SAID SOLIDS AND CAUSING AN UNVAPORIZED PORTION TO COAT AND ADHERE TO SAID SOLIDS AS A LAYER OF OIL WHICH HAS BEEN REDUCED IN VOLUME; AT LEAST PARTIALLY COKING SAID COAT OF OIL; OVERFLOWING COATED FINELY DIVIDED SOLIDS FROM SAID COKING ZONE INTO A CALCINING AND STRIPPING ZONE; IMMEDIATELY CONTACTING AND MIXING SAID OVERFLOWING SOLIDS, 